Protection techniques are either 1+1, where a single session is protected by duplicating the resources required by the session which are used to send a second copy of the signal, and hence recovery from failures is instantaneous, or 1:N, where resources for a single session are shared between N sessions, but this requires the detection of the failure, and determining which session should use the backup facilities. The first technique is fast, but requires at least 100 percent extra resources. The second technique is more efficient, but slow since the management and control planes must be involved.
What is needed is a protection method that uses less resources such as the 1:N method, but which has the speed of the 1+1 method.